Take Queens, one of New York City's five boroughs. With its dynamic clash of cultures, cuisines and tongues, it could easily be the most diverse place in the world.

But Daniel D'Oca, urban planner with Interboro Partners, a Brooklyn-based architecture firm, really likes that Queens is an "open city."

"It's just the most exciting place, though it's not beautiful in a traditional way," said D'Oca. "It seems to work on so many levels."

D'Oca co-wrote the forthcoming book, Arsenal of Exclusion and Inclusion, which examines how community builders use arm rests, "No Smoking" signs and apartment size, among other subtle designs, to welcome some groups while shutting out others, from Hasidic Jews to blacks and even frat boys (see the fascinating blog here).

So whereas Weschester County, New York, a place renown for exclusionary tactics, only offers high-priced multi-bedroom homes, Queens sits on the opposite end of the spectrum. The boro offers a wide variety of housing options for any person, rich or poor. For renters, there's no shortage of affordable studios and one-bedroom apartments. Families can easily move in to single-family detached homes or duplexes.

Another plus is that Queens' "come one, come all" structure makes it easier for all sorts of races and ethnicities to put their own stamp on it. Richmond Hill, for example, became a center of culture nearly overnight. And that's how it should be, said Armborst, the Interboro partner.

"These buildings can quickly change meaning, which is exciting to see in itself," he said, noting that even an "unspectacular" lot can suddenly become a center of community in Queens. "That's what cities should be, an open condition, fostered by new groups."